NEW YORK – The stock market posted its biggest drop in a month on concerns that tighter lending in China could endanger an economic recovery. Disappointing earnings from IBM and Morgan Stanley added to investors’ angst.

At the same time, a spike in the dollar pushed commodity prices sharply lower Wednesday, hurting stocks of energy companies and materials producers.

The Dow Jones industrial average fell 122 points from a 15-month high but ended well off its lows for the day. Demand for safe havens like government debt rose, pushing yields lower in the Treasury market.

File photo / Associated PressA Wall Street sign is shown in New York. The stock market slumped Wednesday on concerns that tighter lending standards in China could endanger an economic recovery. Disappointing earnings results from IBM Corp. and Morgan Stanley added to the market's angst. Stocks have posted sharp swings since last week as investors try to determine the overall direction of the market. The Dow fell 101 Friday and jumped 116 points Tuesday.

The latest slide came as concern grew that China’s efforts to keep its economy under control could hurt a global recovery. A top banking regulator said Wednesday that China will increase monitoring of banks as it tries to prevent speculative bubbles in areas like real estate. Last week China took steps to restrict runaway lending as a way to cool that country’s rapid growth.

Investors are also questioning whether a 68.2 percent gain in the benchmark Standard & Poor’s 500 index in the past 10 months has been too much. Those doubts are intensifying as more companies report results from the final three months of 2009 this week. The early read is that cost-cutting has again helped boost profits, but revenues remain disappointingly weak.

IBM Corp. led the Dow lower. The company reported late Tuesday that its earnings rose 9 percent from a year earlier, while sales rose less than 1 percent. The company’s forecast was seen as cautious.

“We might see profitability out of companies this season but we’re not really seeing revenue growth,” said Dan Cook, senior market analyst at IG Markets in Chicago.

Banks posted mixed results. Bank of America Corp. reported better results and said credit conditions were improving, but also said the economic environment is “fragile.” Wells Fargo & Co. sounded an optimistic note on consumer resilience, but Morgan Stanley fell short of expectations.

According to preliminary calculations, the Dow fell 122.28, or 1.1 percent, to 10,603.15. The Dow had been down as much as 208 points.